1. Field of the Invention
The present invention relates to a microbolometer with a cantilever and a method of manufacturing the same, and more particularly, to a microbolometer having a three-dimensional cantilever, which is an improvement to a conventional two-dimensional cantilever, and a method of manufacturing the same. Using the three-dimensional cantilever in accordance with the present invention, mechanical stability of the microbolometer can be improved, so that it is possible to manufacture a thinner structure of the microbolometer and accordingly a fill factor of a sensor of the entire structure can be increased.
The present invention is derived from the work supported by the IT R&D program of the Ministry of Information and Communication and the Institute for Information Technology Advancement (South Korea) [Project Management Number: 2006-S-054-02, Project title: Development of CMOS-based MEMS processed multi-functional sensor for ubiquitous environment].
2. Discussion of Related Art
A basic operation principle of an uncooled infrared sensor is to detect variation in temperature of a sensor through absorption of incident infrared light. The uncooled infrared sensor can be classified into a microbolometer type, a pyroelectric type, a thermopile type, and so on, depending on a temperature variation detection mechanism. Since the magnitude of a reaction signal of the microbolometer is determined based on variation in temperature of the sensor, the sensor should be thermally isolated from the circumference in order to maximize detection efficiency. For this purpose, in general, a sensor has a MEMS structure with a cantilever providing thermal insulation function. Structure of the conventional uncooled microbolometer is schematically shown in FIG. 1. As shown in FIG. 1, the conventional microbolometer includes a two-dimensional cantilever providing thermal insulation and mechanical support functions. However, while such a planar cantilever has good horizontal distortion characteristics, it has weak vertical distortion characteristics. This is because the cross-section of the cantilever has a small vertical inertia moment.
In order to manufacture a high performance microbolometer, thermal insulating characteristics should be improved. For this purpose, the thickness and width of the cantilever should be minimized and the length thereof should be maximized. However, when the planar cantilever becomes thinner or narrower, it can be easily distorted, so that the deviation between sensor pixels can be increased. When the distortion of the cantilever is serious, the microbolometer structure becomes in contact with a substrate, so that the thermal insulation thereof may fail. Therefore, in order to manufacture a high performance microbolometer, mechanical stability of the conventional planar cantilever should be improved.